1. Field of the Invention
This invention relates to an ink tank on which an ink remaining amount detection apparatus is provided.
2. Description of the Related Art
Various proposals have been made for an ink remaining amount detection apparatus for an ink tank of the type wherein electric current for detection flows between a pair of electrodes provided in an ink tank so that presence or absence of remaining ink is detected based on the value of the electric current flowing through the ink. An ink remaining amount detection apparatus which employs electrodes, however, is complicated not only in the structure for embedding the electrodes in the ink tank and the structure for leading out wiring lines from the electrodes but also in an electric circuit, and a high cost cannot be avoided.
Also an apparatus for optically detecting the remaining amount of ink is already known. FIG. 7A schematically shows an exemplary apparatus of the type just mentioned. Referring to FIG. 7A, the apparatus shown includes an ink detection section 11, a light source 12 and a light receiving element 13. The ink detection section 11 is provided at a portion of an ink tank or of an ink flow passage and is formed from a light transmitting material. The light source 12 and the light receiving element 13 are disposed on the opposite sides of the ink detection section 11, and transmission light through the ink detection section 11 is detected by the light receiving element 13 to detect presence or absence of ink from presence or absence of light or from the intensity of light. A light emitting element or a like element is employed for the light source 12.
However, where a light source for visible rays is used for black ink, there is no problem in detection of presence or absence of light or of the intensity of light. However, if infrared rays are employed, which are less likely to be influenced by disturbance light, some black ink transmits infrared rays therethrough, and discrimination of presence or absence of the ink cannot be accomplished. Further, infrared rays cannot be used for some color ink.
FIG. 7B schematically shows another apparatus wherein a beam of light of a particular wavelength is employed. Referring to FIG. 7B, the apparatus shown includes, in addition to an ink detection section 11, a light source 12 and a light receiving element 13 which are all provided in the apparatus shown in FIG. 7A, a filter 14. In the apparatus, the light source 12 for visible rays and the filter 14 are provided in combination such that light conforming to the color of object ink is used. However, the apparatus is influenced readily by disturbance light, and is complicated in construction and consequently requires a high cost.